skip to main content
Distribution Canal Water Quality
Water Quality
Distribution Canal Water Quality
Distribution Canals have water quality methods to model salt by calculating the total salt mass of the inflow, diversion, return flow, and outflow. Routing methods (No Routing and Time Lag) are provided to route the salt through the canal.
The Water User can currently only model salt.
Note:  There are no user-selectable methods on the Distribution Canal. The water quality methods are specified on the aggregate and is performed identically on all member elements. Automatic links are created between the aggregate and elements.
Slots
Following are descriptions of the slots associated with salt.
Inflow Salt Concentration
Type: Series Slot
Units: Concentration
Description: Salt concentration associated with the inflow to the Distribution Canal
I/O: Input, set by a rule, output or propagated via a link
Inflow Salt Mass
Type: Series Slot
Units: Mass
Description: Salt mass associated with the inflow to the Distribution Canal
I/O: Output only
Outflow Salt Concentration
Type: Series Slot
Units: Concentration
Description: Salt concentration associated with the outflow from the Distribution Canal
I/O: Input, set by a rule, output or propagated via a link
Outflow Salt Mass
Type: Series Slot
Units: Mass
Description: Salt mass associated with the outflow from the Distribution Canal
I/O: Output Only
Delivered Flow Salt Concentration
Type: Series Slot
Units: Concentration
Description: Salt concentration associated with the delivered flow from the Distribution Canal
I/O: Typically output and set to the routed inflows salt concentration. But, it could be input or set by a rule.
Delivered Flow Salt Mass
Type: Series Slot
Units: Mass
Description: Salt mass associated with the delivered flow from the Distribution Canal
I/O: Output Only
Return Flow Salt Concentration
Type: Multi Slot
Units: Concentration
Description: Salt concentration associated with the return flow to the Distribution Canal
Information: When there are multiple links to this slot, the subslots will be shown. The first column is the sum column, which is not relevant as these are concentrations not mass.
I/O: Typically propagated from the linked object. If not linked, it can be input, set by a rule or it will default to zero.
Return Flow Salt Mass
Type: Series Slot
Units: Mass
Description: Salt mass associated with the return flow to the Distribution Canal
Information: Output Only
I/O: Not Linkable
Seepage Salt Concentration
Type: Series Slot
Units: Concentration
Description: Salt concentration of the Seepage
I/O: Input, set by a rule, or propagated across a link.
Seepage Salt Mass
Type: Series Slot
Units: Mass
Description: Salt Mass of the Seepage
I/O: Output only
User Methods
There are no water quality user methods on the Distribution Canal.
Note:  There is not a separate water quality routing method. The selected flow routing method is used to determine the water quality routing dispatch method.
Dispatch Methods
Following are the available dispatch method.
Note:  If the Flow Routing method is Storage Time or Variable Storage Time, an error is issued as these are not supported.
* Solve No Routing Salt
This method is available when the Flow Routing method is No Routing. This method computes the Outflow salt given the Inflow Salt Concentration.
Required Known slots
• Inflow
• Outflow
• Inflow Salt Concentration
Required Unknown slots
• Outflow Salt Concentration
Method Details
Inflow Salt Mass is set at the current timestep by multiplying the Inflow volume by the Inflow Salt Concentration.
If Delivered Flow Salt Concentration is not input or set by a rule, then it is set to the Inflow Salt Concentration.
When a non-default Seepage method is selected and the water quality approach is Propagate Salt (on the aggregate), Seepage Salt Concentration and Seepage Salt Mass slots are available. If Seepage is positive, the Seepage Salt Concentration is set to the Inflow Salt Concentration. If Seepage is negative, the Seepage Salt Concentration must be specified possibly by a link to a slot on another object. If Seepage Salt Concentration is linked but not valid, the reach exits the dispatch method and waits until the seepage Salt Concentration is available from that object. Seepage Salt Mass is computed from the Seepage Salt Concentration and the Seepage.
Note:  Although there are Seepage Routing methods, these only serve to compute the Seepage at the current timestep. In general, Outflow = Inflow - Seepage. Thus, the Seepage Salt concentration does not need to be routed; it is just the value at that timestep.
Then, for each constituent, if the concentration and the flow is valid, the mass is computed. Otherwise the mass is considered zero, but not set.
Finally:
(9.1)    
Finally, Outflow Salt Concentration is computed from the Outflow and Outflow Salt Mass.
* Solve TimeLag Salt
This method is available when the Flow Routing method is Time Lag.
This method computes the outflow salt at the current timestep based on inflow salt from previous timesteps and diversion and return flow salt at the current timestep. Lagging on this object is required to be an integer number of timesteps.
Required Known slots
• Inflow
• Outflow
• Inflow Salt Concentration
Required Unknown Slots
• Outflow Salt Concentration
Method Details
Inflow Salt Mass is set at the current timestep by multiplying the Inflow volume by the Inflow Salt Concentration.
Next, the inflow at the previous timesteps is checked. If either the Inflow(-Lag) or the Inflow Salt Concentration(-Lag) are not valid, the method is exited to wait until they become valid. If they are both valid, then the routedSaltMass is computed using the Inflow(-Lag) and Inflow Salt Concentration(-Lag).
If Diversion Salt Concentration is not input or set by a rule, Diversion Salt Concentration is set equal to the lagged Inflow Salt Concentration, i.e. Inflow Salt Concentration(-Lag)
Then, for each constituent, if the concentration and the flow is valid, the mass is computed. Otherwise the mass is considered zero, but not set.
Finally:
(9.2)    
Finally, Outflow Salt Concentration is computed from the Outflow and Outflow Salt Mass.
Note:  No Seepage Salt is modeled for the Time Lag method.
 
Revised: 06/03/2019